Rotary engine heat sensing arrangement

ABSTRACT

A heat sensor is strategically mounted in a rotary housing of a rotary engine so as to closely sense heat in the hotest housing region.

United States Patent 1 1 Haglund June 3, 1975 ROTARY ENGINE HEAT SENSING [56] References Cited ARRANGEMENT UNITED STATES PATENTS [75] Inventor: Robert J. Haglund, Birmingham, 1,366,894 1/ 1921 Schlaich 73/347 Mich. 2,407,810 9/1946 Boddy 73/347 2,957,348 10/1960 Walker 73/347 Asslgneei General Motors Corporatwn, 3,588,296 6/1971 Toyama 123/801 Detroit, Mich. 3,715,178 2/1973 Jones 123/801 22 F1 d: F b. 8 1974 1 1e e Primary ExaminerC1arence R. Gordon PP N04 440,666 Attorney, Agent, or FirmR0na1d L. Phillips [52] US. Cl. 123/8.47; 123/801; 123741.15; AC

73/ 347; 123/805 A heat sensor is strategicafly mounted in a rotziry [5 Int. Clhousing of a rotary engine so as to losely en e heat of Search in thg hotest housing region 3 Claims, 4 Drawing Figures SHEET 1 PATENTEDJURB 1975 888; 9 1

ROTARY ENGINE HEAT SENSING ARRANGEMENT In rotary engines, it has been found desirable to quickly detect an excessive heat condition that could adversely effect the rotor housing. particularly where the rotor housing is made of aluminum. Heretofore, it has been common practice to locate a heat sensor at some location in the engines coolant system, such as in the water pump body, but not in the rotor housing. In such an arrangement the heat sensor is normally connected to operate a gauge. and it has been found that the gauge reading can actually drop if coolant is lost or if coolant circulation stops. On the other hand, in the case where there is a boilover with a normally operating cooling system, the pegging of the tempera ture gauge may not be observed by the operator.

An object of the present invention is to provide a rotary engine heat sensing arrangement which closely senses heat in the hotest housing region whether or not there is coolant.

Another object is to provide a heat sensor mounted in a rotor housing of a rotary engine so as to sense heat in the hotest housing region by both convection and conduction through the coolant and when there is no coolant in this region by both radiation through the coolant space in this region and conduction through housing structure.

Another object is to provide a heat sensor mounted relative to a rib in the hotest region in a rotor housing so as to closely sense heat in this hotest region by both convection and conduction through the coolant and when there is no coolant by both radiation through the coolant space in this region and conduction through the rib.

These and other objects of the present invention will be more apparent from the following description and drawing in which:

FIG. 1 is a combustion-side elevational view of an internal combustion rotary engine having a heat sensing arrangement according to the present invention.

FIG. 2 is an enlarged view taken along the line 2-2 in FIG. 1 with parts broken away.

FIG. 3 is an enlarged view of the heat sensing arrangement as shown in FIG. 2 with additional parts bro-,

ken away and also includes a schematic of the heat sensing electrical circuit.

FIG. 4 is a view taken along the line 44 in FIG. 3.

The heat sensing arrangement according to the present invention is readily suited for internal combustion rotary engines of the type shown in FIGS. 1 and 2 which generally include in the case of a two-rotor engine a pair of similar rotor housings 10, an intermediate housing 12, a front housing 14 and a rear housing 16 which are all secured together by bolts 18. Each of the rotor housings has a two-lobed internal peripheral wall 20 as shown in FIG. 2 and there are provided oppositely facing end walls 22 at the interfaces of the intermediate housing 12 and the front housing 14 in one case and the intermediate housing 12 and the rear housing 16 in the other case that cooperate with the respective peripheral walls to define a pair of cavities. A crankshaft 24 is rotatably mounted near its opposite ends in the front and rear housings 14 and 16 and has eccentrics 25 located in the respective cavities, these eccentrics being angularly spaced 180 apart. A threelobe rotor 26 is rotatably mounted on each eccentric 25 and has two parallel sides 28 opposite the respective end walls and three peripheral faces 29 opposite the re spective peripheral wall. Each rotor 26 has an internal tooth phasing gear 31 on the outboard side whose center is on the rotor axis and meshes with an annular external tooth phasing gear 32 which is freely received about and concentric with the crankshaft and is secured to the engine s housing, the stationary gear 32 for the front rotor being secured to the front housing 14 and the other stationary gear 32 for the rear rotor being secured to the rear housing 16. The rotary phasing gears 31 have one and one-half times the number of teeth as the stationary phasing gears 32 with the result that the rotors and the crankshaft turn in a fixed phase relationship while the rotors planetate with a fixed relationship to the rotor housing with the rotors turning at one-third the speed of the crankshaft and the two rotors phased apart. The rotor faces 29 and the housing walls 20 and 22 cooperate to provide three working chambers 34 that are spaced about and move with the respective rotors within the respective rotor housings while varying in volume as the rotors planetate, there being provided suitable gas seals on the rotors as shown in FIG. 2 to seal these chambers from each other.

Describing now the induction system, an air-fuel mixture is delivered to intake passages 41 in the intermediate and end housings by a suitable carburetor and intake manifold arrangement, not shown; the intake passages 41 terminating in side intake ports 42 that are located opposite each other in the respective end walls. Upon rotor rotation in the direction indicated by the arrow in FIG. 2, the air-fuel mixture is sequentially, periodically admitted to the working chambers 34 as they expand by the traversing motion of the rotor sides relative to the intake ports whereafter the chambers then close to their intake ports and contract to compress the thus trapped mixture in readiness for ignition. Combustion by spark ignition is provided by an ignition system which has two spark plugs 44 mounted in each of the rotor housings 10 to ignite the mixture in each chamber. Sequentially ignition of the air-fuel mixture in the chambers is effected by the spark plugs receiving timed ignition pulses from a distributor 45 which is driven by the crankshaft 24. The electrodes of the spark plugs 44 are open to the chambers through the rotor housings internal peripheral wall 20 and are peripherally spaced thereabout either side of the peripheral walls minor axis 46 so that one plug is said to lead the other. With combustion, the peripheral wall takes the reaction to force the rotor to continue rotating and eventually each working chamber following the power phase is exhausted during the exhaust phase through an exhaust port 47 to an exhaust passage 48 in the respective rotor housing. Each exhaust passage 48 then directs the exhaust gas to an exhaust manifold, not shown, that is secured to the rotor housings.

Internal cooling of the engine is provided by a water pump 50 which is belt driven from the front end of the crankshaft 24 as shown in FIG. 1. The pump pushes coolant from a radiator, not shown, through internal passageways in the engine housings which include peripherally spaced, axially extending cored passages 52 in the rotor housings 10 that are separated by radial ribs 53. The coolant is then returned to the radiator where it is cooled before being circulated again through the engine. In this engine the rotor housings are the most difficult to cool with the heat being unevenly distributed thereabout and the zone of highest heat flux being in the rotor housing region on the combustion side immediately around the spark plugs 44. Since the bulk of the heat rejected to the coolant is concentrated in this small region of the rotor housing, a lack of coolant circulation can cause sudden adverse affects on housing structure that would not occur so soon in a reciprocating piston engine. For example, where the rotor housings are made of aluminum and the intermediate and end housings are made of cast iron and there occurs an excessive heat condition either because of loss of coolant or coolant circulation, it has been found that axial collapse of the inner peripheral wall may occur when the intermediate and end housings resist the thermal expansion of that wall and the rotor housings compressive yield strength is exceeded. In the case of iron rotor housings, cracking may occur in this hot region around the spark plugs.

According to the present invention, a heat sensor in the form of a bimetal switch 54 is mounted in each of the rotor housings between the leading and trailing spark plugs 44 so that it is in the region of highest heat flux. As best shown in FIG. 3, bimetal switch 54 has a heat input body 56 of metal such as brass having a high coefficient of heat transfer The body 56 has the configuration of a cylinder 58 having a closed end 60 and a taper threaded portion 62 remote therefrom. A bimetal strip 64 is attached within the cylinder 58 to the closed end 60 and at its contact end is arranged opposite a contact strip 66 which is mounted in a cap 68 of nonconducting material over which a portion of the metal body is flanged for attachment thereto. The switch 54 is connected in series with a DC power supply 70 and a lamp 72 which is visible to the operator.

To accomplish the objectives of closely sensing excessive heat in the event of loss of coolant or coolant circulation, the bimetal switch 54 is strategically mounted in the rotor housing relative to the rib 53AB that normally divides the coolant passages 52A and 528 that are located between the two spark plugs 44. As shown in FIGS. 2, 3 and 4, the threaded portion 62 of the sensor engages a complimentary taper threaded hole 74 through the outer wall 76 of the rotor housing while the unthreaded area of cylinder 58 is received with space for coolant at diametrically opposite locations in a radial hole 78 through the rib 53AB and is open to the coolant passages 52A and 52B on opposite sides of this rib. The hole 78 is formed by drilling through the hole '74 in the outer wall 76 and terminates at the radially outwardly facing side 79 of the important inner wall 20. With the bimetal switch 54 tightly threaded in place, space for coolant is also provided between the closed end 60 and the outer side 79 of the inner peripheral wall 20. Thus, the only metal-to-metal contact between the heat sensor and the rotor housing is at the threaded engagement with the outer wall 76 but the bimetal strip 64 is nevertheless very sensitive to thermal inputs from the inner wall through its most direct heat input area 60.

During normal operation with coolant circulation, the bimetal strip 64 will be heated by convection and conduction through the coolant but not sufficiently at normal engine temperatures to cause it to close on the contact strip 66 to light the lamp 72. However, in the event of a sudden increase in temperature of the inner peripheral wall 20 such as may occur when there is a loss of coolant circulation, the bimetal strip 64 because of the close proximity of its heat input end to this wall will quickly receive heat inputs therefrom by both convection and conduction through the coolant across the short coolant path from wall 20 to heat sensor end and at a predetermined temperature, the switch 64 will close to light the lamp 72 to advise the operator.

Furthermore, because the cylindrical body 58 is mounted centrally relative to the rib 53AB, heat from the inner wall 20 is conducted very quickly through this rib to the threaded portion 62 and thence to the bimetal strip 64. This heat path is relatively insignificant when coolant is present in the passages 52A and 52B. But if, for example, the coolant level drops below this high heat zone of the rotor housing or a steam pocket forms in this region, this heat conduction path through metal in cooperation with the radiant heat path across the space normally occupied by coolant then provide an effective means of heat transfer to the bimetal switch for its operation in detecting overheating.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims.

I claim:

1. An internal combustion rotary engine having a sta' tionary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a spark plug mounted in said rotor housing for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas therefrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs between said inner wall and said outer wall, and heat sensor means including a heat input body connected to only said outer wall in the hotest region of said rotor housing and received with space completely thereabout in a hole in one of said ribs so as to be open to coolant in the coolant passages normally separated by said one rib, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said one rib and the connection of said heat input body with said outer wall.

2. An internal combustion rotary engine having a stationary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner peripheral wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a pair of spark plugs mounted in said rotor housing at peripherally spaced locations for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas therefrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs between said inner wall and said outer wall, and heat sensor means including a heat input body connected to only said outer wall between said spark plugs and received with space completely thereabout in a hole in one of said ribs so as to be open to coolant in said coolant passages between said spark plugs, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said one rib and the connection of said heat input body with said outer wall.

3. An internal combustion rotary engine having a stationary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a pair. of spark plugs mounted in said rotor housing at peripherally spaced locations for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas therefrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs therebetween said inner wall and said outer wall including a pair of coolant passages and a normally separating rib located between said spark plugs, and heat sensor means including a heat input body threadably connected to only said outer wall between said spark plugs and received with space completely thereabout in a hole in said rib between said spark plugs so as to be open to coolant in said coolant passages between said spark plugs, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said rib between said spark plugs and the connection of said heat input body with said outer wall.

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1. An internal combustion rotary engine having a stationary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a spark plug mounted in said rotor housing for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas therefrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs between said inner wall and said outer wall, and heat sensor means including a heat input body connected to only said outer wall in the hotest region of said rotor housing and received with space completely thereabout in a hole in one of said ribs so as to be open to coolant in the coolant passages normally separated by said one rib, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said one rib and the connection of said heat input body with said outer wall.
 1. An internal combustion rotary engine having a stationary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a spark plug mounted in said rotor housing for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas therefrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs between said inner wall and said outer wall, and heat sensor means including a heat input body connected to only said outer wall in the hotest region of said rotor housing and received with space completely thereabout in a hole in one of said ribs so as to be open to coolant in the coolant passages normally separated by said one rib, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said one rib and the connection of said heat input body with said outer wall.
 2. An internal combustion rotary engine having a stationary body comprising a rotor housing having an outer peripheral wall and a multi-lobed inner peripheral wall and a pair of end wall housings having oppositely facing internal end walls cooperatively defining a cavity, a crankshaft rotatably mounted in said stationary body having an eccentric located in said cavity, a multi-apex rotor rotatably mounted on said eccentric having sides opposite said end walls and a plurality of faces opposite said inner peripheral wall, means for causing said rotor and said crankshaft to turn in a fixed speed relationship while said rotor planetates with a fixed relationship to said rotor housing, said rotor faces and said end walls and said inner wall cooperating to provide a plurality of working chambers that are spaced about and move with said rotor within said rotor housing while varying in volume as said rotor planetates, said stationary body having an intake passage that is opened by said rotor to said chambers as they expand to deliver an air-fuel mixture thereto, a pair of spark plugs mounted in said rotor housing at peripherally spaced locations for igniting the air-fuel mixture in said chambers, said stationary body having an exhaust passage that is opened by said rotor to said chambers during their contraction to receive exhaust gas thereFrom, peripherally spaced axially extending coolant passages in said rotor housing spaced by radially extending ribs between said inner wall and said outer wall, and heat sensor means including a heat input body connected to only said outer wall between said spark plugs and received with space completely thereabout in a hole in one of said ribs so as to be open to coolant in said coolant passages between said spark plugs, said heat input body having its most direct heat input area at the inner end thereof spaced opposite and closest to the outer side of said inner wall so that said heat sensor means senses the heat of said inner wall by convection and also conduction through coolant between said most direct heat input area and said inner wall and when there is no coolant by radiation through the space normally occupied by coolant and also conduction through said one rib and the connection of said heat input body with said outer wall. 